


Feels Like Drowning

by Nillegible



Category: Harry Potter - J. K. Rowling, Shadowhunters (TV), The Mortal Instruments Series - Cassandra Clare
Genre: Alternate Universe - Hogwarts, Auror Valentine, Blue-Eyed Alec Lightwood, Flooding!, Gryffindor Jace and Izzy, Head Boy Magnus, Hufflepuff Alec Lightwood, Hufflepuff Simon Lewis, Magical Sabotage, Nearly Everyone's a prefect, Prefect Alec, Random Sortings for Minor Characters, Ravenclaw Max, Slytherin Magnus Bane
Language: English
Status: Completed
Published: 2018-06-04
Updated: 2018-06-04
Packaged: 2019-05-18 06:36:36
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 8,804
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/14847642
Author URL: https://archiveofourown.org/users/Nillegible/pseuds/Nillegible
Summary: Alec only meant to borrow a textbook from his new boyfriend, he didn't have anything else to do in the Slytherins' Dungeon. That it was after hours, at nearly 2 a.m. was purely a coincidence. (stop smirking, Raphael, it really was!)It was just really bad luck that they chose the night that the windows in the Slytherin common room decided to fail.





	Feels Like Drowning

**Author's Note:**

> Okay, I totally don't know why I'm posting something in this fandom, except maybe that I have only wanted to write/read about the Slytherin common room's windows failing since I first read the Chamber of Secrets. Back in 2004, probably. Why it had to be a TMI crossover with BAMF Malec and Raphael, I haven't a clue, but I quite love this AU.

It’s terribly late as Alec follows Magnus down several flights of stairs. Magnus is holding aloft a lantern to light their path. Alec has never been to the Slytherin common room before. He’s been to see Izzy and Jace in Gryffindor tower often enough over the years, and just this year he’s been to see Max in Ravenclaw a few times to make sure he’s settled in. He’s always been aware of the vague location of the last house’s location, since prefect’s patrols always tended to be concentrated in the regions where students were most likely to frequent, but he’s still a little surprised when Magnus leads him to a completely bare, entirely non-descript stone wall. His surprise must have shown on his face because Magnus stops mid-story to say, “It’s not a magic door-knocker or a vengeful vinegar barrel, but I’d say it’s the best concealed of the lot. Glancing back at the corridors they had just walked down, Alec nods. “I can imagine. There’s nothing remarkable about this place at all.” At Magnus’ smile he rushes to add, “No offence! It’s really well hidden.”

“Broceliande,” says Magnus to the wall. A door sized block slid away, and Magnus walks through.

“Why do you think the houses are so well hidden?” asks Alec, stepping in behind him. An oddly strong damp smell meets Alec at once. “Sweet Merlin the windows,” says Magnus, and Alec moves forward to see what he means.

There’s water seeping in from the tall windows that lead into the lake. For a moment Alec just stands there beside the Slytherin Head-boy, staring in horror. It’s just after two, the fire has burned low and the greenish light from the lamps are reflecting off the sodden carpets. But for the two of them, the Slytherin common room is completely empty. The lake beyond the windows are pitch black except for the little rivulets seeping down it, and the spiderwebbing cracks, which glint green in the light of the lamps above. “Which way are the dorms?” says Alec in a whisper. He can’t draw enough breath to ask louder. Magnus’ voice is just as soft but there is a thread of steel within. “That staircase down. Boys to the left, girls to the right. Saying ‘Myrddin’s blood’ will let you into the girls’.  _Expecto Patronum_.” Alec is running for the door before the burst of white light from Magnus’ patronus fills the room.

Off the carpet, the polished stone floors are slippery, but Alec’s wordless  _evanesco_  clears the damp for only a moment before the water seeps back. He rushes down the spiral staircase to find nearly a foot of water on the corridor below. “ _Point me Catarina._ ” He whispers. He splashes through the water, mindless of the freezing water, as his wand leads him to the seventh-year girls’ dormitory. Saying  _Myrddin’s Blood_  before he knocks doesn’t seem to do anything, but nothing bad happens when he knocks on the door, then opens it with an  _alohamora._ “Catarina Loss?” he calls from the door and no one reacts. He splashes a few feet inside before the green curtains on the nearest four-poster slip open. The seventh-year prefect peers out. She must not have been sleeping deeply, because she looks somewhat alert and is holding up her wand. “What’s wrong?”

“The windows in the common room are failing. Magnus is…” he trails off as he realizes he has no idea what Magnus is doing. “We need to evacuate. There’s water on the floor,” he adds, just as she climbs out. Catarina takes only a moment, standing in the calf deep, freezing water. “Did you wake the boys?” Alec shakes his head. “Okay, start with the seventh years, tell them to grab a first year and go. Then work your way down.” Alec nods and splashes noisily on the way out. Several of the other four posters shake as their occupants must be woken by the sound of voices. “And Lightwood! Use bubble head charms!” yells Catarina.

Alec has the vague feeling that the water is rising, but it’s not moving too fast so he stumbles his way to the boys’ half of the corridor. He tries the door he assumes is the seventh years, but he must have miscounted because he finds his own classmates instead. Raphael has fallen asleep sitting up, leaning heavily against his headboard, and he’s the first to awaken when Alec calls out. “Everyone, wake up! We need to leave the dungeons immediately!”

Raphael, who didn’t have to push aside his curtains, sees the problem at once. He stares at the filling dormitory floor, then at Alec. “It’s the windows in the common room, we need to leave immediately, I don’t know if it’ll  _hold._ ”

“You woke the girls?” he asks, and a few of the other sixth year boys look outside. “Holy  _shit_ ,” says Jeremy Blackthorn. 

“Catarina said you should grab a first year or two then get out. And to use bubble head charms. You’ll take care of it?” Raphael nods, and Alec slips out to wake the seventh years and tell them to help the second years.

When he slips back out after waking the fifth-years, there’s considerably more noise and people in the corridor; with so many students trying to get out. All of them are pajama-clad, and many are clutching a few personal belongings. Their voices echo oddly around and over the water.

Raphael, who he’d seen walk four tiny first years out, is back before he can get to the next room. He says, “I’ll get the third years. Put the bubble head on the fourth years yourself, I don’t know if their spells will hold.” The water has only risen to mid-thigh, but Raphael looks deadly serious. “You think it won’t hold?” asks Alec, but Raphael has already disappeared inside.

Alec wakes the fourth years and makes them grab their wands. With the door open, the sounds of the other Slytherins is loud in the small chamber. “Can we grab our things?” asks Ethan Rosier. “You don’t have a minute to lose, just get out!” he says. He holds the boy still and incants ‘ _caput bublio’_ just as he had for the first three boys in the dorm. Ethan continues to scowl at him from inside the fish bowl like bubble, green eyes furious, but Alec is already striding to Philip Carstairs. “Bubble head charm, hold still,” he says, then casts. When he’s done with the lot, only half of them have left the room.

“Did you not hear me? Leave your things and get out,” he says. Philip holds up a fluffy but large white cat. Alec bubble-head charms it, and adds an impervious, because he can’t see it going well for the feline otherwise. Outside, several more students walk by in single file. Raphael peers into the room, catches Alec’s eye and points to his own Bubble head charm. Sheepishly, Alec casts one on himself.

Rosier is still rummaging in his own trunk, so Alec angrily yells, “ _Pack! Diminuendo!_ ”and all of the boy’s things fit neatly into his trunk then shrink down into a palm-sized box. “ _And twenty points from Slytherin every minute you waste here!”_ Alec’s voice sounds menacing, but the boy sneers as he walks out. Then Philip is tugging quietly on his sleeve. “Alec, please do mine too?” The other children are also staring at him hopefully, and Alec wants to scream. “Please!” says the boy and he looks desperate, so Alec does. Six packing and shrinking spells later, he gets them out the door and into the corridor. He takes the cat out of Philip’s arms. “You will need your hands free to get out. I’ll bring him.”

Across the way, Catarina has what must be the last of the girls, alongside the other Slytherin prefect, Lydia Branwell. “Is that the last of them?” she asks-yells-really, to be heard above the din of falling water, younger Slytherins, and the bubble head charms, when they meet in the middle. Alec turns around because he hasn’t checked, but Raphael splashes up from behind him, with two third years. “The dorms are empty this side,” he says loudly. Aiming his wand behind the girls he casts a  _homenum revelio_ , and nods that it’s clear that way as well. Just then, Professor Fell’s voice sounds from above. “Brace yourselves!” he cries, and he must have used a  _sonorous_  because his voice is loud, clear above the rest of the din, “Stay calm, just swim to the doorway, follow Magnus, just-” his magically magnified voice cuts off with a huge crash and screams, screams that echo loudly, and then cold, freezing, heart stopping cold and pitch darkness. His feet rise off the ground. The furball in his hands twists and claws viciously, frightened beyond belief and Alec feels it tearing into his skin.

Alec is instantly disoriented, but his wand tip lights up with his unconscious, desperate need for light. He sees Lydia’s pale, stunned face, but then he notices the churning in the water above and sweet merlin there were children in the stairwell. He pushes his way ahead against the unforgiving water, until he finds the first ones, two boys who clutch at him in terror. He pushes upwards, trying to help them forward, but they don’t move. He glances below to where he sees faint light, but the others had had several students as well, it was unlikely they could help. Pushing and pulling, he gets them up several more stairs before he finds three more. One of them is the fourth year Philip, and when Alec mouths the incantation and waves his wand he catches on and casts a  _lumos_  of his own.

By the light of his wand, Alec sees that one of the others- Alec vaguely thinks his name is Thomas- seems to be struggling for breath. Alec has a moment of panic where he fears his bubble head charm had failed. But no, the bubble appears fully intact, he doesn’t understand- he gestures at them to move but Thomas, wide-eyed, isn’t responding – A third light appears from above, a stream of bright red light, and Alec sees Magnus swim down towards them. He gestures impatiently, so Alec nudges the coherent ones towards the head boy, who reaches down to help them out. He slides his arm around Thomas’ torso, uses one leg to kick the boy’s feet outwards, and bodily pulls him along as he half swims and half climbs the remaining stairs. Alec feels strangely vulnerable like this, both his arms full and technically defenceless.

 

* * *

 Magnus’ first spell is an emergency patronus to the Slytherin head of house. The message is simple: ‘Windows cracking, come at once. Bring help.’ He doesn’t pause to contact anyone else because surely Ragnor would alert the rest of the staff, and he doesn’t have a moment to lose. Striding closer to the pitch-black windows, he raises his wand to perform a testing spell. He’s not going to toss an unconsidered haphazard  _reparo,_ not when so many lives are at stake. Magnus is the top of his class for a reason, he knows every spell like he’s had centuries to master them, his magic is as easy as breathing. The spell he casts brings the old wards and safety spells into glowing relief against the black glass. He has to hold back a cry of alarm because not only have the ancient spells splintered, there’s a distinct tendril of hostile magic woven through the faltering protection spells. Feeding them might strengthen the dark spell, but he might also take the remaining spells holding the windows together out entirely if he tries to unravel that first. He wastes two precious minutes trying to make sense of it, trying to find a point where he can isolate the malicious magic from the ones keeping the lake at bay, but he can’t. Whoever had done this had had time, and that was a luxury Magnus could not afford. Behind him, he hears Catarina’s clear voice as she leads out the younger students. “Keep count Cat! There are two in the infirmary already!” he calls, still trying to make up his mind about the next course of action.

He raises a second barrier just behind the windows. It’s nearly futile, Magnus knows. Should he match his own magic against a lake this old he would die in short order. There was something about water that made it dampen and consume magic (the effect increasing exponentially with volume) and a spell without a physical tether like glass would not last long. And yet, even a few extra minutes could mean enough time for more students to leave. Magnus is willing to take that chance.

“Magnus, what the hell are you doing?” Ragnor. Magnus rarely thinks of the head of house as a professor; the man had been a fifth-year prefect back in Magnus’ first year. “Cat and Alexander are evacuating the children, you should help them, Ragnor,” he says. The older man makes a curt sound of assent and Magnus hears him walk away.

He’s just finished the last spell when Ragnor returns. “Less than half are out. I’ve ordered them to go three floors up, I met Garroway, he said he’ll lead them above the potential water line. None of the other staff are here yet. How much time?” Magnus turns back to the windows, and the extra barrier he’s put up and calculates. Water is still seeping through both but most of the lake water is still out there instead of inside. “About four minutes,” he says.

“Well shit,” says Ragnor and for a moment they stare at the students streaming out of the spiral staircase and across the common room. They’re in various states of disarray, some barefoot as though they hadn’t had time to find their shoes. “Spell all the glass from breaking, we won’t be able to see it underwater.” There’s something fierce and haunted in Ragnor’s aspect that spurs Magnus to move faster.

Once he finishes, (and why was there so much glass in their common room anyway? Lamps and shelving and so many little knickknacks…) he strides over to the stream of students, encouraging them to hurry and promising that it’ll be okay. There are so many frightened faces; at any other time, Magnus would be kinder, more reassuring. But right now, they have to move. The stones are slipping them up so they’re walking slowly- too slow, there’s no time – so Magnus conjures a glowing red rope. He magically fastens one end to the wall beside the dormitory stairs and the other to the banister of the outside staircase. “Grab the rope and keep moving; we’re running out of time!” The rope makes it faster, a little, but it’s not enough. The tell-tale sign of cracking sounds like a gunshot and Magnus turns to see that the windows have given way. All that’s holding the lake back now is Magnus’ jury-rigged barrier, which would in less than a minute allow all the water through. The only relief was that the splintered glass would be kept back by it.

He wants to tell them to run but they can’t, if they fall now they could die, they’d just… “Hold tightly to the ropes! The lake is coming in,  _don’t let go,_ ” he yells. He waits in silence, his heart beating loudly, staring at the thick, shimmering wall of lake water. He doesn’t know what to do. He has been acting on autopilot, performing the necessary tasks that had to be done and now he feels lost.

“Magnus, you need to lead them out. It’ll be pitch dark in a moment,” says Ragnor’s voice. He casts a bitten out _sonorous_ and cries, “Brace yourselves! Stay calm, just swim to the doorway, follow Magnus, just-”

There’s a roaring crash, Load enough to stun him and then he’s slammed by a wave of freezing cold and an eerie, just _faintly_ red darkness. His bubble head charm is intact but the impact makes him lose his breath and his footing. Disoriented by the churning water, the weight of it pressing against him, and the ghostly shape of the detritus lit solely by the red light of his rope, it takes Magnus a moment to light his wand.

The room is trashed. Most of the Slytherins have been swept off their feet, but even dazed, they’re still clutching the rope. Pippa alone must have lost her grip, but she’s holding onto Gwendolyn’s robes with her eyes screwed shut. He swims towards them to help. He gestures the students out. He casts warming charms on the most disoriented, but mostly he just wants them out.

Only then does he realize that no one new has come up the staircase since the water came in. Sweet Merlin, Alec and Raphael both were still down there. Magnus hasn’t been keeping count, so he’s not sure who else. He swims towards the pitch-black hole in the wall, where he knows the spiral staircase is.

The children have frozen in their panic, that’s all it is. Magnus breathes easier when he sees a grumpy looking Alec trying to nudge the students into coming up. Alec’s eyes are vividly blue, shining in his own wand light, and he’s clutching a cat. Magnus pulls the kids causing the block-up towards himself. 

* * *

 Jace wakes up feeling freezing cold, heart pounding, in his four poster. He gasps and casts a Lumos, confused by the sensations that had woken him. Alec. Something had happened to Alec. He stumbles out of bed, still disoriented. Sharp stinging pain in his arm helps ground him (because Jace has always been strange like that) but also frightens him, because he can't even imagine what Alec-that effing moron- is doing right now.   
  
It's late, long past curfew, so Jace doesn't wake anyone else. He'll find his Parabatai himself.   
  
He sprints down the stairs (Gryffindor tower is annoyingly high up, sometimes), through a secret passageway, down another flight of stairs. He hesitates a bit when he realizes that he's not heading to the Basement, but turns the left that leads to the dungeons anyway.  
  
He finds a whole gaggle of students, all of them Slytherins, along with Professor Garroway.   
  
"Professor?" he asks, because he doesn't understand what's going on.  
  
Garroway ignores him, instead directing the older students to lead the younger ones to the great hall. Most of them are soaked, at least below the waist, and some are completely drenched. Then Garroway turns to him.  
  
"Mr. Wayland, good. I want you to head back down until you reach the water level, help the students out. Just use a few charms, get them warm and dry, and send them up.  
  
It's obvious what has happened, and Alec is also down down down according to the tug on his soul, so Jace goes. The landing below is above the water, but four steps down the stairs are completely submerged. Three more students stumble out of the water, dripping and shivering.  
  
"Hey there, it's alright," he says, and he casts a warning charm and a drying charm on them, and cancels the bubble he'd charm . They still look so miserable, that he calls, "Ditsy!" When the house elf appears, he tells her, "I'm so sorry Ditsy…but could we trouble you for some hot chocolate?" The elf takes in the scene with her huge eyes and then squeaks. "But of course sir! The poor children! Ditsy wakes all the house elves sir, please wait." She disappeared with a crack. Jace offers the slytherins a smile. "It'll be okay. Once Ditsy gets you your cuppa, just climb up this flight of stairs? Professor Garroway is here, he'll get you sorted."   
  
He can vaguely see more shapes coming closer, and he wades a little closer to help them out the last bit. He gives them all the same treatment; the eleves take care of the cocoa, and he helpfully tells them that there are more students up in the great hall.  
  
He's helped about a dozen students (does someone have a count? How will they know if everyone is out and safe?)  
  
There is the sound of footsteps running down the staircase behind him, and he sees Headmistress Herondale. She's in a dressing gown and practical footwear. The. Headmistress watches as Lotso hands the most recently dried child (a fourth year?) a  cup of hot cocoa, and Have sends her upstairs.   
  
"Bless you, Jace Wayland," she says, pulling out a map. Jace leans over to see little dots, each labelled, walking through the map. He peers closer and sees Magnus, and Alec.  
  
They were steadily (if rather slowly) making their way out. Jace returns to his task as a new pair rise from the water.  
  
It changes when a child comes out gasping, "There were Grindylows, professor! They tried grabbing us!" There's a deep bruise on his ankle, the leg of his pajama pants shredded where the grindylow must have grabbed him and he'd tried to get away.  
  
He wants to dive in, he hasn't felt anything more worrisome than what woke him up, but he's scared that that could change. He tells himself that he's being stupid. Alec could handle a few grindylow.  
  
Professor Herondale looks angry. Her lips are pressed into a thin line, and her eyes flinty. She's looking back into the map, and Jace looks over her shoulder.

* * *

Outside the stairwell, if possible, is worse. The wooden chairs and tables are bouncing against the ceiling but so much else, the couches, books, and lamps float haphazardly and menacingly around the room. Someone - Alec assumes it was Magnus - has strung a glowing red rope across the room towards the entrance so that they can guide themselves out the door, and there are several students clutching it as they make their careful way out. It doesn’t help that Alec finds himself floating higher without the low ceiling of the spiral staircase to keep him in place, so he’s moving farther away from the rope. He tries to swim back down, but he’s not strong enough to pull their combined weight that deep, and he’s exhausted. He turns to Thomas, whose breaths have evened out, but has his eyes are screwed tightly shut. Alec shakes him softly until he opens his eyes. Looking into frightened blue eyes, Alec points at the rope, where the remaining students are carefully crossing.

Magnus is looking up at the two of them, an uncharacteristic frown on his face while Catarina and Raphael cajole the students towards the exit with brightly lit wands. It’s that extra light, with the higher vantage from where Alec and Thomas float suspended that Alec notices the creeping shadows that move with deliberation, unlike all the other floating junk in the room with nowhere to go. He stares at them in confusion until he identifies them; Grindylows. They must have crept in through the broken windows.

He lets go of Thomas to flash his wand tip, and Magnus, who was already looking up at him looks alarmed, but Alec points deliberately at the creatures. He sees four of them, now that he’s looking for them, creeping carefully towards the line of children. While he watches Magnus try to find what he’s pointing to, he sees Professor Fell. He must have returned from outside to get the last students. Alec waves at him to try and bring his attention to the Grindylows. Alec tries shooting a spell at one, which scurries away. His fingers are freezing though, and his magic feels uneasy. This far away and underwater, he’s too afraid to try the others that are close enough to the students for him to worry.

Thomas, in the meantime must have found his courage, because he squeezes Alec’s shoulder, and starts to swim back down on his own. Alec follows him, keeping his eyes on the Grindylow heading a little too close to Raphael for comfort. Further ahead, Professor Fell shoots a bright spell at something near Rosier’s ankles, temporarily brightening the room. Magnus reaches out to grasp Thomas’ outstretched hand, pulling him to the sturdy rope, and then reaches out again for Alec. Relieved, Alec grasps the familiar hand stiffly, and lets Magnus draw him to relative safety. Philip’s cat still has its claws dug deeply into Alec’s upper arm, but it’s not moving, so he can deal. The immediate threat here are the grindylow, and Alec scans for them as he moves. He feels hypersensitive, every brush of debris against him feeling like they might be the brittle fingers of a grindylow…

Hyperaware, skimming the unlit edges of the room for danger, he sees the shape of a child in the darkness. Then he notices the bare reptilian skin of a webbed hand, in the flash of light from someone else’s spell. DADA has not been Alec’s best subject for years for nothing, so he has a stunner aimed at the creature before it springs for them. The spell hits but doesn’t do any damage. The creature merely slips to one side, graceful as a fish in the aquatic environment.

Catarina notices, and Alec sees her cast a shield charm. She’s still further from the door though, and her spell will only hold around herself and the students with her. She shoots a panicked look at Alec and the others who are still out of range. The Kappa bounces of the shield, giving Alec a good idea of where it is, but uses that momentum to head straight for Thomas. His own stunner misses, but Magnus’ spell- was that an incendio?- grazes one misshapen hand.

It only seems to enrage the creature, which snaps its beak. The Kappa moves further away, watching. Alec can see the malice in its dark eyes, where he can just make out the scales and pale skin glittering in the dark water. He casts another spell from defence, but that doesn’t have any effect either. Alec is beginning to panic, particularly since the Kappa is circling around. Every book, every teacher has told Alec that the way to defeat a Kappa was to tip it over so that the water filling it’s misshapen head poured out. That it was the source of all the Kappa’s magic.

No one had ever told him how to defeat one _underwater._

He sees Magnus leave the rope- Merlin, what was he doing? – to head towards the creature. He was casting as he went, and Alec understands when a cage twists into shape around the water demon. For a moment it looks like it would work, and then a grindylow grabs at Magnus’ ankle. He looks down, concentration lost, and the Kappa uses brute force to twist and bend the bars of the cage apart and fly out, furious, reaching towards Magnus with an inhuman snarl-

Another spell from behind (Aline? Raphael?) and Magnus’ quick shield charm bring it to a stop moments before it could take a bite of his flesh. Alec realizes that he’s let go of the rope and swum closer, unintentionally. The Kappa turns, and for a moment it looks into Alec’s eyes before it lunges for him instead. He can see it then, the hate, the _hunger,_ and then it reaches out with red-clawed hands- and the answer comes to him. He casts a bubble head charm on the Kappa, and then he’s being clawed, both by water demon and terrified feline, spinning backwards from the force of the lunge- and the Kappa goes still.

It floats horizontally above Alec, jarringly peaceful and unmoving, limbs limp and graceless in the water. Gravity, momentum, and the bubble head charm had succeeded in emptying the bowl atop the Kappa’s head, and it was powerless now. Safe.

Alec doesn’t move for a moment, just floats there, heart beating double time as he stares at the unconscious face of the Kappa. That had been so close, _so_ close, Merlin’s beard – he doesn’t know how long he stays there, but then he feels himself being tugged. He turns, and sees Magnus, only Magnus, staring up at him from the still glowing rope. The spell brings Alec near enough to grab hold, and then Magnus is taking the cat from him, and running a hand up Alec’s arm, his cheek. He squeezes Alec’s hand over the rope, finally, and then starts pulling himself towards the door. Alec follows.

The dungeon corridors outside are also flooded. Alec should have expected this. The rope extends to the banister of the staircase at the end of the corridor, and from there they use the railing to help themselves out.

* * *

They scramble out of the water halfway up a random staircase shortly after Professor Fell, the last students to leave the dungeons. Several teachers and house-elves have gathered, and in quick succession, Professor Garroway performs a drying charm and a warming charm on him, drops a cloak over his shoulders, and tries to hand him a mug of hot chocolate that he waves away. Turning wildly, he finally sees Alec receiving the same treatment from Professor Herondale, while a house-elf brings over his cocoa. A familiar blond is standing _way_ inside Alec’s personal space, running his fingers over the tears in Alec’s robes. He’s keeping up a steady stream of insults, but Alec smiles, “’m fine, Jace,” and reaches for the cocoa. He drops the mug the moment he takes it though, and only house-elf magic keeps him from scalding himself when the mug slips through his fingers with a whispered, “ _Whoops.”_

“Alexander?” asks Magnus, alarmed, stumbling closer. He feels unsteady, too warm and still freezing cold; safe, yet still scared witless. Alec sits down heavily on the stair. It was more of a collapse, really. If Jace hadn’t grasped Alec’s upper arm and lowered him gently to the floor he might have just fallen. Magnus is on his knees before his boyfriend before he realizes how he got there, one step lower than Alec, and he pulls Alec’s hands into his own. The cuts are deep, the blood welling from them anew atop the dried blood left behind from the drying charm. Healing charms would fix it though, Kappa claws were fortunately not magical in any way.

Alec’s skin feels warm enough as Magnus pats him down to check, but the signature bright blue eyes are cloudy and unfocused. “’vryone’s out?” he asks, and he slurs the words, and Magnus’ panic is only building at seeing Alec, eternally strong and dependable this disoriented. He’s cradling Alec’s face in his hands, ready to demand an answer when Alec tips his head forward to lightly rest his forehead against Magnus’. “Shld sssleep. Tired.” He hears a relieved giggle slip out of his own mouth, Alec had been tired even before Magnus tempted him down to the Slytherin common room to borrow a textbook.

Professor Herondale clears her throat, and Magnus looks up to see her wand is inches from his face. He recognizes the pale lavender of a diagnostic spell, twisted around her wand-tip, waiting. He’s too close to Alec for her to work the spell correctly. He tries to right himself, and to his surprise he needs Professor Garroway’s assistance to stand up and step away from Alec. “Exhaustion and superficial cuts, dear, and no significant blood loss,” says the headmistress after she’s carefully waved her wand above Alec’s head in circles three times. Jace has his arm around Alec the moment her spell ends.

“Mr. Wayland, if you could escort Mr. Lightwood to the hospital wing while I finish up here…”

Magnus finds himself leaning heavily against Professor Garroway. He’s relieved and completely done. It can’t have been more than half an hour since he and Alec had entered the Slytherin dungeon and yet he feels like he’s aged years in the interim. Garroway tightens his grip on his arm, and Magnus looks down in confusion before he realizes that the room is tilting oddly back and forth. Alec has slumped over onto his adoptive brother and Magnus frowns but then he’s being led carefully away and up the stairs. Ragnor is with them after a minute, and Magnus recounts as much as he can about the spells he had found on the windows, and what he thought could have caused the failure.

Garroway takes him all the way to the great hall, where he’s deposited carefully on a strangely squishy purple sleeping bag, between a scowling Raphael, and Catarina.

“And where’s Lightwood?”

“Hospital wing. How many?” asks Magnus. Raphael must understand because he answers, “None of the first and second years, because they made it out before the windows. But Mia James, Rosier, Penhallow, and Yarrow had to go. Magnus, what happened to Lightwood?” Magnus peers at his friend blearily. But Raphael didn’t  _like_ Alec. Why did he care? He doesn’t notice his eyes fall shut.

“Alec is fine, Raphael. He’s being taken to the infirmary for minor injuries and magical exhaustion. He should be fine by morning.” Everything’s really dark, but he can still hear Garroway. How weird was that? Oh, his eyes were closed, now there’s light. The fake sky in the great hall shows thousands of little stars. Was Raphael…smiling? Everything goes dark again, and Magnus hears the sound of a zipper. For some reason that tickles Magnus, why do wizards need something as muggle and mundane as zippers? The sleeping bag must have been drawn up around him because he’s encased in warm softness. A hand brushes against his forehead, and he hears, “Idiota,” in a quiet fond voice before he drifts away.

* * *

Professor Fray, the Gryffindor head of house, must have posted the message in the early hours of the morning. “All the classes for the day have been cancelled. Breakfast will be served in the common room, do not leave your common rooms unless specifically asked to. - Headmistress Herondale.” Isabelle takes one look at the sign attached to the bulletin board and walks straight to the portrait hole. It doesn’t let her out. There isn’t instant chaos, because not even half the house is awake this early but the surprised and frightened murmurs begin. The only times that the students are in lockdown is when there’s a direct threat to their safety. She’s running up the stairs to Jace’s dormitory at once. Her brother’s bed is empty. She can’t say she’s terribly surprised. But she _is_ furious _._

What are the chances that her other idiot brother is also involved in whatever mess this is?

It appears that Helen, the 6th year prefect had started a head count, she comes into the room counting heads (or lumps under blankets). She glances at Isabelle and says, “All the girls are accounted for. Did you check the boys?” “No. I know Jace is missing, but I don’t know if anyone else is too.” Gryffindors had a horrible track record for pulling dangerous stunts, since _brave_ and _idiotic_ have only a very fine line between them, and most Gryffs weren’t too bothered with minutiae. It takes Helen a minute

The Lightwood owls are all up at the owlery, and there’s no way to get to them with the portrait hole sealed. Fortunately, Gwen had chosen to keep her owl in her room last night, and Isabelle borrows it to send a message to Ravenclaw tower, to ask Aline if everyone in her house was okay. Helen is with her as she writes, and Izzy rolls it up only after Helen nods her satisfaction. The message assures Aline that every Gryffindor (Helen included) is safe and accounted for. When the owl returned, Isabelle would ask after Alec and the Hufflepuffs. 

The restlessness in the room only grows as the news spreads to sleeping students who come down to see for themselves. The buzz of conversation swells, and Isabelle takes refuge by dropping down in Clary’s corner. The redhead usually has an armchair, a chair, and two tables at least staked out with half done paintings and art supplies, and everyone had mostly given up on trying to evict her years ago. Izzy and Clary hadn’t gotten along when they first met, but they’ve genuinely grown to be good friends. Her presence is comforting. Clary doesn’t mention Jace going missing at all. They’re both sort of used to Jace’s idiocy and tendency to dive into danger by now. There’s nothing to say. Her mouth is tipped down in the corners, but she’s only doodling in a sketchbook with charcoal, the lines angry and dark. “What is it?” asks Isabelle curiously, because it’s mostly unrecognizable. It is a poorly kept secret that the Frays had a bit of a gift which came out when they drew or painted. “Cold water. Lots of cold water, Izzy,” says Clary, with a vague sort of certainty. “Do you think someone drowned?” she asks. Clary continues to draw jagged cracking lines. “No?”

They’re interrupted as several voices from around the fireplace call out for Clary. Isabelle follows Clary over to the fireplace, where Simon’s head is bobbing in the flames. “I checked with the Ravenclaws, everyone’s fine. Max is fine,” he says first, and Isabelle relaxes. “Are you guys okay?”

“Jace is gone, Simon,” Isabelle tells him. Simon droops a little. “Okay…but did you…uh…have an extra person? Any Hufflepuffs?” It’s instantly clear that Simon means Alec. If Alec had been back at the Basement, it would have been him fire-calling to check on Izzy and Jace.

“So Alec’s gone too?” she asks and Simon doesn’t have to answer, his expression gives it away. Isabelle strangely feels a little _less_ worried. Her brothers could take care of each other. But… “I saw him after patrols last night, and he was fine. Didn’t he go back with you, Simon?”

“He said he needed to talk to Magnus…I guess it’s possible that they found whatever it was that’s freaked the staff out and that’s why he hasn’t come back. Could you... I mean…” he trails off. But there’s genuine worry in Simon’s voice. She’d always been aware that Alec had adopted the easily frazzled muggle-born as an extra sibling halfway through her first year, but Isabelle can see now how deep Simon’s bond with Alec must be. He looks pretty close to hyperventilating. “We’ll tell you if we hear anything, Si,” says Clary. “Keep your mirror on you, it’ll be faster.”

“I did that first! You didn’t pick up, I only saw red fabric…anyway, I’m going to try the Slytherin common room. Hopefully, no one will stab me once they see my face.” Simon’s face vanishes with a pop and Isabelle feels a leaden, ashy suspicion settle over her. Clary’s drawing… had looked an awful lot like broken glass.

* * *

Alec isn’t in the Basement. Simon is well aware that the other houses believe themselves to be superior at all sorts of things, but the one thing Hufflepuff House holds sacred is keeping their family together. It takes them only a minute after the first Hufflepuff finds the sign for everyone in the house to know two things; their sixth-year prefect was missing, and something terrible had happened outside. Simon checks on Ravenclaw first since that would be the first thing Alec would want him to do if he was here. He assures the Ravenclaws that everyone’s fine, ascertains that Alec isn’t there but Max is blissfully asleep, and then tries Gryffindor. It’s harder to speak to Izzy and Clary, who look at him accusingly like he’d lost Alec on purpose. He hadn’t. Alec and Magnus have been spending more time together recently and Simon had honestly thought they’d just wanted a little privacy. He would have followed them into the dungeons if he’d had the faintest idea that something was wrong.

Simon leans back on his heels and contemplates the flames. He can’t decide if finding out that Jace is also missing is a relief or cause for more concern.

He’ll have to check the last house, ask Raphael if he’d seen the two of them. It’s alright even if Alec isn’t in Slytherin; there are loads of other places he could be, Simon tells himself. He could be with the professors; Alec was a shoo-in for head-boy next year, and Jace was the Gryffindor prefect. He could have gone to the infirmary to keep someone company, or even due to a minor injury… “Simon?” says Julian Blackthorn, the seventh year Hufflepuff prefect. “The food’s here, d’you want to come and eat?”

“Just a moment,” he says, and tosses another pinch of Floo powder into the fireplace. “Slytherin Common room,” he says, once the fire turns emerald green. Before he can lean closer though, the fire hisses and sparks, and then a huge billow of steam pours out. Julian grabs Simon and pulls him bodily away from the green vapor. Simon can only stare in horror. Julian banishes the smoke, but the fire is out. It looks like it was doused in…pond slime, and it smells awful. Wet, and burnt, and muddy. Simon doesn’t have the faintest idea what just happened.

Professor Carstairs must have come in when the fire went wild because he’s suddenly by Simon’s side. “Are you alright, Simon? What on earth were you doing?” The professor’s silver eyes run over him carefully. “It was just floo powder! I talked to Aline and Clary and I just wanted to ask Raphael if he’d seen Alec because he didn’t come back with me and Raphael wasn’t on patrol last night but he might have seen them together afterward and the fire just-” Simon waves at the sodden smelly fireplace, “-and Alec’s missing!” Simon probably sounds a little hysterical. His voice is definitely oddly pitched.

“Alexander is  _fine_ ,” says Professor Carstairs and he sounds vehemently certain. “I spoke to him just a few minutes before I arrived here.” Simon relaxes, immensely grateful that the professor had chosen to start with the most important thing. “And Jace?” he asks, to be sure. “Also fine. He’s with Alexander.”  The complete terror he’d been suppressing since he’d woken up and realized that Alec was missing slowly winds down. He opens his mouth to ask the professor to explain, but Julian says, “Come eat, Simon,” hauling him towards the platters of breakfast food laid out on the tables near the armchairs.

Professor Carstairs looks around at all the other Hufflepuffs. “Is everyone here?  Alright. Firstly, Alec Lightwood is fine, he spent the night in the infirmary because he overtaxed his magic, but he should be back before lunch. You don’t have to worry about him. In fact,  _no one_  in the school is hurt permanently, and we can credit part of that to Alec’s own actions last night.” The professor looks grave, and it’s such a rare sight that every Hufflepuff is listening to every word.

“Last night, there was an accident in the Slytherin common rooms. For those of you who don’t know, the Slytherin dorms are in the dungeons, much further down than we are, so their windows look into the lake. Those windows cracked last night, and their entire dormitory is flooded. Fortunately, Magnus Bane and Alec noticed the fractures when there was only a little water inside, and they, Professor Fell, and the other prefects got all of the students safely outside.

“Since this happened at around two this morning the Slytherins are currently sleeping in the Great Hall. We elected to let them sleep in because they had a rough night, so you had breakfast served here. You can go back to the hall for lunch in a few hours.”

“Why did you lock us in though, professor?” asks Simon, and the professor turns to him. “I’m sorry we worried you, Simon, we should have told you everyone was safe and then locked you in. We were just in a hurry. We suspect that the windows to the Slytherin Dungeon were deliberately sabotaged, and we didn’t want you wandering around the castle while whoever did it could still attack. Magnus says he saw a deterioration spell mixed into the usual wards, and although since the windows are underwater so we can’t verify it, he’s probably right, and casting a spell like that underwater would be extremely difficult magic.”

“How would  _locking us in_ save us if the common rooms were the ones being attacked?” asks Julian.

“All of you were asleep, so I don’t blame you for not noticing, but I did come in earlier this morning to check for curses and to trigger the blackout wards. Only I and Professor Herondale can enter until I deactivate them. A team of six Aurors has been checking the rest of the castle since sunrise, which is why it’ll be safe for you to be let out around lunchtime.” He looks so sincere that Julian looks embarrassed for asking. Now that Simon looks closer, he can see that Professor Carstairs is…exhausted. He must have been awake all night. Gemma fills him a plate, and he accepts it gratefully.

“So, the Slytherin common rooms are just underwater? Are they all okay? Magnus, Raphael-” he waves his fork around to mean everyone – “Everyone.”

“They’re all fine. Most of them are still asleep, but I did speak to Magnus and Raphael, they’re helping Professor Herondale.” Simon offers the professor a relieved smile. He’s halfway through his potatoes when he remembers Clary.

“Oh shit, Izzy is going to kill me,” he cries, running for his dorm. He misses the professor’s fond smile as he bounds through the circular doors. 

* * *

 

The sky in the Great Hall is only just lightening when Raphael wakes up. It must have been Magnus that woke him accidentally because he can see Magnus striding away from him and towards the main doors, where several professors are in heated discussion with some witches and wizards he doesn’t recognize. Muttering about idiots, Raphael follows him.

“Auror Morgenstern, this is Magnus Bane, our head boy. He’s the one who noticed the curse that caused the accident,” says the headmistress. “You can be assured that I have absolute faith in his spell-work and identification.”

“Very well, Headmistress. Mr. Bane, could you describe to us the spells that you used on the window?”

“The ones I used, or the ones I found on the window?”

“I’m sure I can ascertain that for myself. The ones you used would be sufficient.”

“I used a  _magikos revelio_ ,  _clara animea,_ and  _implicatorum_ on the windows. Once I identified the binding spells as the ones that had sustained the most damage, and that I was unable to separate it from-”

“That won’t be necessary, Mr. Bane. What else did you cast on the wall? Please take your time, if the events of last night are difficult to remember so soon.”

“I didn’t cast anything else on the wall,” says Magnus, his voice cold. “I put up my own barrier, but it was eighteen inches away from the unstable magical barrier, which was above the minimum recommended distance of fifteen inches.”

“You want us to believe that a seventeen-year-old managed to put up a barrier of that strength without any physical tether? Most likely the spells warped as you cast. If high powered protection spells were too close to a failing magically enhanced physical barrier, even momentarily, it would explain the sudden splintering failure that Professor Fell was kind enough to describe to me.” There’s something about the man that just makes Raphael want to lunge for his throat. With his teeth.

It might be the manic glittering of the Auror’s eyes.

Professor Fell interrupts, “That would  _not_ explain the failure that I described, if Magnus had triggered the break, it would have been _while_ he cast, not several minutes later.”

“Your disbelief does not change my abilities or what happened, Mr. Morgenstern,” says Magnus. Raphael, who’s been watching the others’ expressions while Magnus and Morgenstern lock gazes, notices Headmistress Herondale looking at him. She tilts her head minutely towards Magnus and shakes her head. Raphael thinks she wants him to take Magnus away but he checks by mouthing: Leave? The headmistress gives a subtle nod.

“I’m sorry to interrupt, sir, but we need the Head Boy. There are things to sort out for the younger kids and since Professor Fell is busy we need Bane.”

“Of course,” says the Auror. “I’m sure Mr. Bane’s expertise will come in handy.” There’s a sneering lilt to his voice and Raphael really does not like this man, but he pulls Magnus away.

“Who’s the asshole?” he asks, when he’s judged that they’re sufficiently far away. The students around them are still sleeping, but Professor Carstairs is talking to three house-elves near the dais where the teacher’s tables usually are, and that’s where Raphael is leading Magnus.

“That’s Auror Valentine Morgenstern. Charismatic, entirely crazy, and the man who ‘accidentally’ abandoned his partner in a werewolf den during a full moon.” Shit, so that was Professor Garroway’s old Auror partner. “There’s no love lost between my father and Morgenstern’s supporters, even though they’re both slimeballs. Political differences.”

That was an understatement. Asmodeus Bane was widely known for having something _other_ in his blood, (something Magnus had inherited in a watered-down version), and was a vocal supporter of people with mixed heritages, like half-elves, or werewolves. It would be admirable if the man wasn’t also evil, the proprietor of a vast criminal empire in south-eastern asia.

Professor Carstairs seems to be giving instructions for breakfast when they reach him. The house elves depart with a bow and a pop, and then the professor is looking up at them. “I’m glad you’re alright,” he says with a smile. “Why are you awake so early? Classes have been cancelled for the day. We’ll be serving breakfast for the Slytherins later, here, but the other houses will get their food delivered to the common rooms.”

“Couldn’t sleep,” says Raphael, shrugging. “Do you need anything, Professor?”

The professor looks at them with his silver eyes. “Well, we do need a permanent place to put the lot of you,” he says. “Professor Herondale wants us to split the students up and have them stay at the other three houses until a more suitable arrangement can be made. Since you know your housemates better than I, if you could prepare a list? I would hate for there to be disagreements.”

“But students from other houses aren’t allowed inside, professor. It’s quite traditional,” says Magnus.

“And yet for some reason, you invited Mr. Lightwood into yours last night, Mr. Bane.” To Raphael’s surprise (and secret glee) Magnus blushes faintly.

“But why not convert an unused classroom into sleeping quarters? We’d at least be together,” says Raphael.

The professor frowns. “Magnus, how skilled would you say the wizard or witch who took down the windows and wards was?”

“Extremely powerful. It wasn’t just complex magic, I think it was cast from the other side of the windows, so they had to have been able to cast it even with the water dampening their magic.”

“Yes. And it’s not just that. Kappa aren’t native to Britain”

“Yes, they’re Japanese. But we do have exotic species in the lake…”

“Not water demons, no. And Magnus- your barrier didn’t fail entirely. No physical objects beside the water itself entered. We had the merpeople verify that.”

Raphael feels a chill as he realizes what that means. He sees Magnus stiffen as though he understands the implications as well. Professor Carstairs nods.

“The house common rooms and dormitories have more protections than even the rest of Hogwarts. That one was taken down and no one noticed… it was sheer dumb luck that you and Alec noticed what had happened. If you hadn’t been late after your patrol…If you’d returned when Lydia and Catarina did, and gone to bed, I mean…We don’t know how many students would have died.”

Raphael tries to imagine it, imagines being woken by icy water filling his nose and mouth while his wand was too far away to be of use, imagines the Kappa and the grindylow sneaking up on them in that confusion…and puts the thought firmly from his mind. Magnus’ sickly-sweet romance with that Hufflepuff had saved them, and he wouldn’t think of the could-have-beens.

“This has to be the most effective attack on Hogwarts since Voldemort brought his death eaters here, and even then, the victims were students of age that chose to fight. We don’t even know who perpetrated the attack this time, either,” – that was true, Raphael realised, even Voldemort had announced himself and his decision to kill before he ravaged Hogwarts. “-and so for your own safety, the other houses are our best bet.”

**Author's Note:**

> I'm probably going to go back and brush up some of these things. I find it strange that they mention only one pet being rescued (I know from experience that the animals are loud and pushy about getting out) but maybe not. In any case, apologies for the names of the side characters, it's been ages since I read TMI, and I only read that series once, so I ran out of ideas. And except for Alec, Magnus, Jace, Clary, Izzy, Max, and Simon, I also sorted people every which way. 
> 
> If anyone sees something awful, drop me a comment, I'll fix it. The next half of the fic should be up pretty soon. I hope you liked it!
> 
> Edit: All of my thanks to onceuponagleekonbakerstreet, Fic4Ever and Elisabeth_erika for telling me that I'd included the last bit multiple times! I don't have a beta reader, and I don't know if I ever would have caught it since I made the mistake while posting, so thank you very much!


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